The Kremlin has launched a campaign to crack down on Russians' access to critical western media, according to a former employee of the country's main state-run news agency.

The RIA-Novosti news agency last weekend reportedly ordered the employee to avoid stories critical of the prime minister, Vladimir Putin, and his United Russia party ahead of the elections.

Following the order, the employee, Grigory Okhotin, resigned his post at Inosmi, a website which translates articles from foreign press sources and is run by the news agency.

"They told me rather clearly not to translate harsh stories about Putin or United Russia," Okhotin said. "Or, they said, you can translate some but soften the headlines and don't put them on the front page." The order came from the RIA-Novosti leadership, Okhotin claimed.

But a RIA-Novosti spokeswoman, Alla Nadezhkina, said the organisation maintained a "neutral position and objective approach". She said published by Okhotin contained "clear distortions regarding the editorial politics of RIA-Novosti and Inosmi, based on his own fantasies". No order had to soften headlines, she said.

Marina Pustilnik, editor-in-chief of Inosmi, refused to confirm or deny the order. "I recommend you look at the website – there is quite a bit of material on the elections and Putin."

The Kremlin has become increasingly nervous about public support as it prepares for a parliamentary vote on Sunday and presidential elections in the spring. Polls show a steady decrease in support for United Russia, as well as for Putin, who is expected to return to the presidency after serving four years as premier.

Most Russians get their news from state-run TV, which is curated by Vladislav Surkov, the Kremlin's ideologist and a Putin ally. But with internet use skyrocketing, many Russians are turning to the web as an independent source of news.

Livejournal, Russia's main blogging platform and a hotbed of opposition thought, came under DDoS [distributed denial of service] attack , an action many bloggers linked to Sunday's vote. The platform last came under large-scale attack in April. "These attacks are against multiple journals worldwide, several of which are political in nature," the group said at the time.

The alleged censorship attempt at the state-run project came as Putin, speaking at his party congress, accused "representatives of some foreign countries" of seeking to undermine Russia's elections.

"You can't pressure the western press, can't ask them to soften their tone ahead of the elections," Okhotin wrote in an essay about the affair, published on a popular blog

alongside internet chat with an Inosmi editor about the censorship order.

The essay was sent to translators, he said, "because you can't just plug up the throat of the Wall Street Journal, the New York Times, the Guardian and other western media".

He added: "It's an astonishing tale that will astonish nobody. I was ready to quit at any minute, since joining nearly a year ago. It wasn't unexpected."